Safety skip control device



Feb. 2, 1932. c. H. WAGNER SAFETY SKIP CONTROL DEVICE Filed Nov. 26, 1928 3 Sheets-Sheet l INVENTOR Wa /w ATTORNEY Feb. 2, c H WAGNER SAFETY SKIP CONTROL DEVICE 3 Sheets-Sheet 2 Filed NOV. 26, 1928 INVENTOR WZhiflWg/W ATTORNEYS Feb. 2, 1932 c. H. WAGNER SAFETY SKIP CONTROL DEVICE 3 Sheets-Sheet 3 Filed NOV. 26, 1928 I NV NTO R Z0315. Wagner ATTORNEYS Patented Feb. 2, 1932 sierra rar Leaves "ersnr CHARLES H. WELGNER, OF WASHTNG'ION, DISTRTC'J OF COLUMBIA, ASSIGNOR TO KOEHR- 1- ING CGIVIPANY, OF MILWA'U WISCONSIN, A COR-PORATIGN 'sarn'ry sKir CONTROL nnvicn Application filed November as, was. Serial 1rd. 321,967.

The lowering of the loading skip of a paving .machine presents a factor of possible danger to attendants of the machine or other persons who are liable to come into its path of downward travel. These ships are of a massive construction and any injury which they might cause a person is necessarily of a serious nature. Occasionally workmen have been killed. There have been heretofore proposed guards or rail means for preventing persons from coming under the skip when the latter is upraised. However, such devices involve complications of structure and control and a ditl'erent type of means is desirable.

I propose toapproach the problem of safeguarding against injury to persons due to downward movement of the skip, from, a different anglethan has heretofore been thought of. Ty idea is to provide instrumentalities which function to cause cessation of downward movement of the skip immediatelythe same strikes against any object. Such means has-the advantage of not only preventing injury to persons, but alsodamage to the skip construction, or any other obj ectsthat might be interposed in its path of movement.

In attaining this end,I provide a guard which is normally positioned a slight distance from the bottom surface of the skip. This guard is so mounted that relative movement between it and the skip, which would be caused by the said guard striking against an obstacle during downward travel, operates certain control mechanism which im mediately causes a halt on the part of the skip. These instrumentaliti-es may take the place of the automatic brake means common ly included in mixing plants of this type for gradually arresting the skip in its downward movement so that it does not strike theground with a jar. When the guard above noted engages the ground, the skip is brought to rest as hereinbefore set out.

It is an object of the invention'to provid novel mechanism for controlling the downward movement of the charging skip. This mechanism is designed primarily to beatfected by the guard and associated instrumentalities previously noted to stop the skip in its downward movement upon an obstacle coming in the path of the said skip, but also provides the added advantage of constituting means for preventing the speed of the skip in its descent from exceeding a certain safe limit. "It is noted that the operationof the control mechanism as last noted, insures the proper operation in accordance with the primary reasons for its presence in the construcwnv It is a further ob ect of the invention'to provide control mechanism as above noted of the'hyd-r'aulic. type. In a preferred embodiment this hydraulic mechanism takes the form of a system of fluid which is circulated by a pump, the circulation controlling the pump rather than the lattercontrolling the former. Valve means are included in the circulation system which may beadjusted to regulate the flow of fluid therethrough so that the rate of descent of the skip cannot exceed a certain safe limit, in a m anner'to be hereinafter more fully set forth. I This valve means, or other valve means, may be availed of to completely cut oil? the circulation whereby descent of the skip is stopped. The pump is connected by driving connections with the skip hoist drum which "causes upward movement of the skip and is effected by the latter in downward movement so that downward movement of the skip causes operation of. the pump, which may be effected by the circulation system as previously noted.

A more detailed'feature of the invention lies in the arrangement of the driving connections between the skip hoist drum and the pump aforesaid. These connections are so designedthat upward movement of the skip in no way affects the pump or hydraulic circulation system, the latter being brought into v operation only upon downward movement of the skip.

I Other features of the invention worthy of note are associated with the provision of operative connections between the guard instrumentalities carried by the skip and the control mechanism. It is essential that these connecting means in no way interfere with the operation of the pivoted skip, and for this connection I have provided novel connecting means.

lVith these and other objects in View as will in part become apparent and in part be hereinafter stated, the invention comprises certain novel constructions, combinations and arrangements of parts, as will be subsequently specified and claimed.

For a full and more complete understanding of the invention, reference may be had to the following description and accompanying drawings, wherein,

Figure 1 is a View in side elevation of a paving machine showing my invention as applied to the charging skip thereof.

Figure 2 is a view in side elevation bringing out particularly the association of the control mechanism with the skip hoist drum.

Figure 3 is a detailed showing, partly in section, developing the construction of the pump means and its relation with the circulation system. Figure 1 is a detail View somewhat enlarged, partly in section and partly in elevation, showing the driving connections between the skip hoist drum and the pump means.

Figure 5 is an enlarged detail showing in section of the control valve which is included in the circulation system.

Figure 6 is an illustration in perspective, somewhat detailed, of the sleeve which is located on the skip axis and constitutes an essential part of the connections between the guard instrumentalities and the control mechanism.

Figure 7 is a View in end elevation of a mixing machine with the skip upraised, parts of the'machine being omitted to more clearly bring out the construction of the guard instrumentalities and the connections between the latter and the control mechanism.

Figure 8 is a diagrammatic showing from the side of the parts essential to the invention, full and dotted line positions bringing out the operation of the guard means.

Figure 9 is a detail showing in perspective of the connections which are affected by the skip hoist cable to effect stop of the skip through operation of the cut-01f valve, and

Figure 10 is a detail view in side elevation bringing out the counterbalanced pivotal mounting of the guard.

While I have shown a preferred specific embodiment of the invention herein, it is to be understood I am not to be limited to the exact constructions illustrated and described, because various modifications of these details may be provided in putting the invention into practice within the purview of the appended claims.

A concrete mixer of the paver type is shown in Figure 1 more or less completely, and this machine includes a loading skip A which is operable to charge aggregates into the mixing drum B of the mixer. A skip hoist drum C is driven from the main power plant D of the mixer through driving connections comprising a shaft 1 and the clutch instrumentalities shown at 2, which are operable to clutch the drum G to the shaft 1. A skip hoist cable 8 is wound on the drum G, the cable being located in the spiral groove shown at 4 so that it is fed evenly to the drum C, and as it is being wound, the said cable will move laterally. The skip hoist cable 3 at its other end is taken up on the large drum 5 which is keyed to shaft 6 which carries drums 7. A cable 8 has each end anchored to one of the drums 7 and each reach of the cable 8 passes over a sheave 9 down to the loading skip, the bend in the cable being positioned beneath the said skip and anchored thereto. It is obvious that the mechanism just described is operable to hoist the skip when the clutch 2 is operated to clutch the shaft 1 to the drum C.

The hydraulic circulation system which constitutes the control mechanism for clownward movement of the skip, comprises the tubing 10 that defines a loop. A reservoir 11 contains some suitable fluid, such as oil, and is connected with the tubing 10 by the union shown at 12 so as to insure the complete provision of the necessary fluid in the tubing. Fluid may be supplied as required through the feed opening shown at 13. A pump as shown at 14 is interposed in the line of circulation of fluid passing through the tubing 10. Obviously, there is a wide variety of pumps which are available for the purpose intended. However, Figure 3 develops one construction of a pump which comprises casing 15 in which are pivotally mounted meshing pinions 16 carried by shafts 17 and 18. The rotation of the pinions 16 causes circulation of the fluid indicated by the direction of the arrows in Figure 8. Referring again to Figure 2, it is noted that the shaft 18 is drivably connected with the pinions 16 in a suitable manner, this being shown in the drawings.

A control valve 20 is associated with the tubing 10 and is operable by an arm 21 to open or close the circulating system, thereby permitting or preventing circulation of the fluid in the latter. To this arm' 21 is connected a link 22 that is connected at its other end to a bar 23 by pivotal connection shown at 24:. The bar 23 carries headed bolts 25 which lit in slots 26 in sliding bars 27 so as to slidably mount the bars 27 on the bars 23. Each of the bars 27 has extending from one end thereof an abutment member or projection 28. A spring 29 of the contracting type has its ends fastened to adjacent ends of the bars 27 so that the spring constantly exerts a force tending to draw the bars 27 towards one another. The purpose of this sliding bar construction just described is to provide a ment therewith of ratchet 43 carried by the a yielding abutment engagement for the cable 3 to engage against as it is wound orunwound from the drum C to actuate the valve through the connecting means comprising bar 23, link 22, and arm 21. In the intended manner of operation when the skip is being raised, the drumC will be wound so that the cable 3 will move leftwardly as shown in Figure 2 to engage the right abutment member 28 to shift thebar 23 to theleft to open the valve 20 thereby permitting circulation in the tubing 10. Upon downward movement of the skip, the cable 3 is unwound from the drum which causes the same to move rightwardly as shown in'dotted lines in Figure 2, whereupon it engages the other abutment member 28 to shift bar 23 tothe right causing a closing of the control valve 20.

The control valve 20 may include adjustment means for regulating the flow of fluid through the tubing 10, although I prefer to avail myself of a needle valve shown at 30 for this purpose. This needle valve is operable to vary the size of the opening through which the fluid'inthe tubing 10 may flow at that point so as to control the rate of flow of fluid through the circulating system. This valve is operated by the operating member shown at 31.

A cut-off valve is shown at 32 and isof the detailed construction illustrated in Figure 5. This valve is operated by an arm 33 pivotally connected to the link 34 that is in operative connection with the guard instrumentalities to be later described. This cuts off valve comprises a casing35 in which is rotatable a valve member 36 having a bore 3'? which may be placed in or out of alignment with the tubing 10, as the case may be. The arm 33 is operatively connected with the valve member 36 to cause rotation of the latter. An adjustable member shown at 38 comprises a threaded screw mounted in a projection 39 that is adjustable to vary the limit of movement of the arm 33. The cutoff valve 32 is designed to be operated by the guard instrumentalities through suitable connections at the proper time to cut off the circulation of fluid in the tubing 10 to cause the stop of the skip in its downward movement.

The shaft 18 has bearing in a bracket 40 carried by the framework of the mixing machine and has loose thereon the pinion 41 which is in mesh with a large gearwheel 42 carried by the drum C. One face of the pinion 41 is provided with a set ratchet 43, which is designed for engagement with a complemental ratchet 44 that is slidably connected to the shaft 18 as shown at 45. A spring 46 abuts against the collar 47 at one end and the ratchet 44 at the other end and affects the latter to cause a resilient engagepinion 41. The driving connection between the drum C and pump 14 just described is suchthat upon upward movement of the skip,

there is no driving relation established due 7,

' art may be availedof to cause disengagement of drum C and shaft 1 when the skip reaches A its charging position. The brake shown at 51 is applied simultaneously withdisengagement of the clutch to maintain the skip in its upraised position. This arrangement of clutch knockout means and brake for the skip hoist drum is a conventional and well known expedient in these paving machines.

Referring nowmore particularly to Figures 7 and 8, it is noted that the skip A is pivotally mounted at 52 so that it may be swung for effective operation, the pivotal mounting 52 comprising a horizontally dis-. posed shaft. Arms v53 connect the shaft 52 with the skip A. Pivotally mounted on'the under surface of the skip A at 54 is a guard 55. The guard is maintained spaced from the under surface of the skip due to the action of springs 77 and suspension means comprising chains 56. This guard 55 comprises a framework 57 of tubular construction and a'meshwork 58 which consistsof wires running crosswise, lengthwise, and diagonally, to provide a guard which of necessity must engage against any person or obstacle lying in the path; of downward travel of the skip. The pivotal mounting of the guard at 54 comprises a shaft59 which has bearing in brackets 60 carried by the skip. Weight members 61 are carried by arms 62, which are for all efiective purposes integral with the tubular structure of the guard 55 so as to counterbalance the latter. The reason for the presence of these weights or counterbalancing means in the construction, is to provide for the easy movement and operation of the guard.

An arm 63 extends from the shaft 59 and has'connected thereto at the end thereof a link member 64 which has its other end fastened to a small lever 65 carried bythe under side of the skip. A second link member 66 has one end fastened to the lever 65 and its other end to one arm 67 of the bell crank 68, which is pivotally mounted on'a pin 69 carried by the skip. The other arm 70 of the .7

bell crank 68is of a yoke construction which ioo is in engagement with sleeve 71 slidable on shaft 52. This sleeve 71 is provided with grooves 72 with which the yoke member and a second yoke member 78 engage. The yoke member 73 is one arm of the bell crank 74L- pivotally mounted on a pin 75, having suitable mounting on the framework of the machine. The other arm 76 of the bell crank 74 is connected to the link 84. The connections between the guard and the link 3%, which is connected with the cut-out valve 32 just described, are designed to operate said valve to stop circulation of fluid in the tubing 10 upon any relative closing movement between guard 55 and skip A, which would be caused by the guard striking against a person or obstacle resting in the path of downward travel of the skip during said movement.

When the skip A is resting on the ground, the guard 55 will be pressed close thereagainst and the cut-out valve 32 will be closed so that no circulation of fluid in the tubing 10 is permitted. Upon the clutch instrumentalities 2 being operated to cause hoisting action of the skip, the skip A. will move upwardly away from the guard 55 as far as permitted by the chains 56. Continued rotation of the drum C causes the skip to move into its charging position. Upon reaching the latter, the cable 3 engages one of the abutments 28 to open the control valve 20. The cut'out valve 82 having been opened when the guard 55 moved to a spaced position from the skip A, the circulation system is now open. During upward movement of the skip the pump 14; has not been affected on account of the ratchets interposed in the driving connections between the drum C and pump 14. Now when the brake 51 is released to permit downward movement of the skip C, these driving connections between the drum C and pump 1 1 are rendered effective so that downward movement of the skip is controlled by the pump 14 and the circulation system. This circulation system has been previously regulated by the needle valve so that the rate of descent of the skip may not exceed a safe limit. Now should for any reason an obstacle or person be in the path of the skip, the guard 55 will strike against such obstacle and be moved relative to the skip. This relative movement will actuate arm 63, links 64 and 66, bell cranks 68 and 74;, and link 34, to operate cut-out valve 32 whereby circulation in the tubing 10 is prevented, stopping the skip. This same action will take place when the guard 55 strikes against the ground and the skip reaches its lowermost limit of travel.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is

1. Safety mechanism for charging skips of the class described, comprising, in combina'-.

tion, a skip, instrumentalities carried by the skip adapted to be operated by engagement of saidinstrumentalities with an obstacle in downward movement of the skip, hydraulic mechanism for controlling downward movement of the skip, connections between the instrumentalities on the skip and the hydraulic control mechanism, and means for causing said control mechanism to be operative only on downward movement of the skip.

2. In a concrete mixing machine of the class described, the con'lbination with a loading skip, mechanism for controlling the movement thereoland instrumentalities carried by the skip operable to affect the controlling. mechanism, of connections between the instrumentalities on the skip and the control mechanism comprising a sleeve mounted on the pivotal axis of the skip, connections between the sleeve and the control mechanism whereby movement of the former causes movement ofthe latter, and connections between the sleeve and the instrumentalities on the skip, said instrumentalities being operable to effect a sliding of the sleeve on its mounting.

In testimony whereof I affix my signature.

CHARLES H. VJAGNER. 

